docs: def url(self, **kwargs):
          """Returns a formatted URL for the Asset's File
          with serialized parameters.
  
          Usage:
              >>> my_asset.url()
              "//images.contentful.com/spaces/foobar/..."
              >>> my_asset.url(w=120, h=160)
              "//images.contentful.com/spaces/foobar/...?w=120&h=160"
          """
  
          url = self.file['url']
          args = ['{0}={1}'.format(k, v) for k, v in kwargs.items()]
  
          if args:
              url += '?{0}'.format('&'.join(args))
  
          return url